1. Field of the Invention
The present invention relates to a microscope apparatus.
2. Description of the Related Art
In general, sample observation using a microscope is performed so that an objective lens is brought close to a sample placed on a microscope stage to magnify a target observation part on the sample. In this case, the objective lens brought close to the sample decreases in depth of focus with an increase in magnification, leading to difficulty in positioning the objective lens to the observation sample. In addition, even a slight change in the distance between the objective lens and the sample will greatly degrade an observation image.
Although the apparent positions of the objective lens and observation sample are very close to each other, the mechanical linkage length of them is very large because of the interposition of many mechanical parts such as a microscope frame, objective lens moving mechanism, and revolver. These mechanical parts tend to change their dimensions due to changes in temperature. As the number of mechanical parts increases, therefore, the amount of change in dimension increases. In addition, as the mechanical linkage length increases with an increase in the number of mechanical parts, this structure is susceptible to vibrations, resulting in a large vibration amplitude.
Even if, therefore, the objective lens is focused on the observation sample at the time of observation, the distance between the objective lens and the sample greatly changes as the dimensions of the respective mechanical parts change with a change in ambient temperature due to the operation of air conditioning equipment. This readily causes defocusing. In addition, when slight external vibrations are applied to this structure, the distance between the objective lens and the sample changes due to a large vibration amplitude. This readily causes defocusing in the optical axis direction or horizontal direction.
For the reasons described above, even if the focus is adjusted on an observation sample at the time of observation using a microscope, as the ambient temperature changes due to the ON/OFF operation of an illumination lamp and the activation of an internal power supply and air conditioner, the dimensions of mechanical parts change to change the distance between the objective lens and the sample. This causes defocusing.